Matched potential electrical control system



Sept. 30 1947., H. F. HERBIG MATGHED POTENTIAL ELEGTRICAL cNTRonsYs'TEM Filed July 7, 1945 SNF. smh SQH tua Patented Sept. 30, 1947 UNIT-ED STATES rares i 2,428,024 'liiA'iciEn -fro'rliNTnd-L CONTROL SYSTEM Henryv F.4 liHerbigLwSummit, ,y N. vassignor toxIn-v ternational Standard Eklectri Corporation, New York, N. Y.,`a corporation of Delaware tplieatidn Jiiy i, 1945', seal Nddoegsizi c oliiis. (o1. 'lic-sis) This invention relates to, electrical control systems in which `a'controlleddevice is actuatedwhen aA-potential applied to thesystema't 'a control station' is matched by a potential applied to the system lat an operating station. 1t is particularly applicable `toautomatic telephone systems, but

may be usedin control systems and especially remotedcontrol'systems of various types, such 'as electric elevzfitor control, control, calculating machines, telegrapnticket and other automatic Print-re and the :like- The invention includes inxgeneral an *actuating deyeethat will notoperatewhen one of the applied potentials is f belaw e ci1tr0f f Value relative tolthefothe potenti ,in onipinationwith means idr lirelfillg opraiia @fthe Qontrol. device by tl'ie'ac'tuating device when d said Vfirstpotential is abovesa selected value in thenoperating range of die actuating dedicati by disconnecting said device. With this arrangement the controlled devi'c' is atatedfonly when'th'e iilirvst potential is een vsaid values, a relationship referred to nfa's unichme.

*More specifically, tnejiiiventidii includes the use of la vacuum tube in the o`actuating device, the

station rpotentialsl o'r ,potentials `deriveigl `from the' 4being applied the @on rdl'giid and catlio bathe con rol'ledjdevicebeing'operate by an'oifle current'whiclll'ows whenever the potential ofthe contrlefrid ,relative to 'tile cathcd'e is 4alcove 'the cntloii value, `in fcombination v' anode from the userid potentiglis-high'r tlia'rii-'a` predetermined value 'above cutoi-.Am

y viitioi is the utilizatioiiof a vacuum til-b' hav1ng"=a sceenerid to provide a simplified contrclsys'tem. In screen grid tubes of the' 'appropriate 'type 'an 'increase in 'the control grid potential above the cut-oivalue produces not only progressively increasing anode Acurrentup to the saturation point but also progressively increasing screen grid current, which however is only arather small fraction of the anode current. The invention includes the utilization of this tube characteristic to obtain the results already described by'employing the system connected to the screen grid and anode, including means operated by the anode lcurrent only when the screen grid current is below a -predetermined value. With this arrangement the system Will not be operated'when the "control grid is at a cut-olf value below which usefulanodecurrent is not generated and likewise v'will be inoperative when the 'screen l startial anode current "eiiniiltdne'usly {genera e This is tidvg'xntageouslfy accomplished fby" ploying a "current responsive actuating devi e; such as a relay, in tnediiddd "jciiuit df tire and'asec'ond current responsive 'd vice,` su'c relay, in the sc're'eng'rid ciruit'ivhich when ac ated by the screen 'grid' iiiijiitwiii cui di h iirst device. The vseconddevice"isselected's Vth t' the screen grid -current `ifi/ill be insufici tI operate it when the r"control"g'dpot" Hal relative-tothe cathode is'withiii trie' matching range.

Trie invention is 'espediallyadvani'ag'dus utilized 'in 'an 'automatic telecommunication sl tern 'in which fa register at "tlle'contrlst provided with a brush? ovd'v'e'r a'seri lar sries' Ndf et points. l The purpose iste halt' `theselector t on a contact point vvl'los'ev fp'otential matches of the point on which the register brush has` s'topped. If the appropriate `pn'ijrit is idle d iig the first ypassage di 'the-selector brush the 'latter will te halted s'sdon agit reacties suoli point; tdt if the latteris :busy lits potential' will 'be @nan ed' and tneselector brush wilientinue'toi'iunt; forth in Patent No. 2,`3 80,950"-of Gerald Dea and in the various applicatinsgdd @patents rev-'- ferred to therein, this "iiiventiqnl isliig'a'iricdifib'ar tion 0f the control .circuits"disclosed'tnerini s 'Other features 'and advantages 'of 'the infn' tion `will app'ear fironl 'the' following 'd'e's'crip considered in connection with the accompany i drawing, which isa diagiamiif'as muclidf a vfitr'ol system as is necessaryffor a clear' undersl'faifdV in'g of the 'present invention.

The drawing Villustrates tleapp-liication 'ofthe invention to an autnitictlephoiie System in? which calling 'and called subs'crlloers zstatidiffs; and2 maybe interconnected-byflneans including. plurality-of selector 'switches 3 and il. The'inu merical -operations of v'the'"seli'ec't'o'rs 'are controlledby 'the 'calling 'sbscribrs' customary impl/ilse sender, kysender "or othrcommon fdrriv ofcon'- trol deviceth'rough theagencybf la register. pro; vided at the centralexchan'ge. The"calling"staf-A tion l is connected to tlie brushes'of vselector 3"E 'y' known switches (not `shownliarida connectingcircuit '5,'and the register is attached t the'c'nl: necting "circuit 5 Fthrough switching Y'lruari's'ff.

The selector switches are "*of the customary type, vhavin-g a bank `of terminals with' Wlii'chia` set rof brusllsc'ooperates. "Infth'e drawings three' brushesar'e sliown ior'selector'sw'rtcli 3; the' lows ermost being designated as T, although the selector may have a larger number of brushes. The selector brushes are moved over the selector terminals including test terminals ST while a magnet P is energized, and are stopped on a set of terminals when this magnet becomes deenergized, this construction and operation being well known.

The register comprises a series of switches successively operable by the calling device in accordance with successive digits of the called number which are dialed by the calling subscriber. Brush RB and a set of terminals RT of one of 4 potential of the contacted terminal ST is above the minimum value at which the potential applied to the control grid will produce sufficient screen grid current to operate relay PCR, the circuit of relay VR will be opened and brush T will continue to travel over the associated terminals ST. However, when the terminal ST engaged by brush T has a potential matching the terminal T engaged by brush RB, relay VR will be energized while relay PCR remains inoperar tive due to the insufficient screen current generthese register switches are illustrated. This is the register switch'which responds to the digitV in accordance with which the illustrated selector 3 is to be set. When brush RB is advanced to- Ward one o-f its ten terminals in accordance with the operation of the calling device at station I, the relay AR l having been energized in the customary manner, a circuit is closed from ground over Vthe right armature and its front contact of relay AR l, the armature and back contact of register relay VR, the winding of selector relay AR and the magnet P .to grounded battery. Magnet P is energized and the brushes of selector switch 3 are driven over the selector test terminals ST continuously in knownmanner until relay VR is energized and breaks the circuit of magnet P. i

The circuit of relay VR extends from the anode of tube V through the back contact and armature of relay PCR, the Winding of relay VR and the left front armature and front contact vof relay AR l to grounded high tension battery HTB l. The winding of relay VR may be shunted by resistor R 5 if necessary to obtain the desired operation. The circuitl of the winding of relay PCR extends from the screen grid of tube V through the back left armature and its front contact of relay AR I to grounded high tension battery HTB 2.

Each of the register terminals RT is connected through a suitable resistor to a source of potential, `and the selector terminals ST are similarly connected, the potentials of successive terminals advantageously Y varying progressively by the same amount, which in the illustrated embodiment is four volts, though it will be understood that thisrparticular potential arrangement may be varied Within the scope of the invention. Either a series of negative potentials or a series of-positive potentials may be employed as indicated.

lThe register brush RB is connected 1to the cathode of tube'V and the selector brush'T is connected to the control grid `of the tube, preferably through a biasing resistor R 2. Brush T is advantageously connected through a high value resistor R 4- to the negative terminal of grounded battery, in order to prevent false operation when the brush T is not in contact with a terminal.

ST. With this arrangement the potential of the register terminal RT selected by brush RB will be applied to the cathode of tube V, and the potentials of the selector terminals ST will be successively applied to the control grid of the tube with an appropriate potential drop across resistor R 2. When the control grid potential relative to the cathode potential is more negative than the value at which sumcient anode currentto operate relay VR will flow, a value which will be referred to as the cut-off value, magnet P will remain in operation and the `brush T will continue to travel over the terminals ST. When the ated at the applied matching potentials. The resultant shift of the armature of relay VR will open the circuit of magnet P and halt brush T on the appropriate selector terminal ST.

In the preferred arrangement illustrated, the matching terminals will normally have the same potential, but the system will be operative even though the conditions actually encountered in practice may introduce slight variations in potential between the two selected terminals, as long as the relative potentials `are within the matching range. The system will also be operative Where the matching potentials are substantially different by employing means such as a suitable resistor to bring the potentials into the desired relationship before applying them to the control grid and cathode of the tube. The resistor R 2 may also be utilized where the matching potentials are substantially the same to produce the control grid bias requisite for most eiiicient operation of certain tubes. n

It will be understood that the invention has been illustrated without complicating it by the inclusion of other parts of the automatic telephone system in which it may be used, an embcdiment of which is illustrated in the abovementioned Deakin application. Certain features which might be added to adapt the illustrated arrangement to particular uses, to produce particular types ofoperation or to adapt the circuit to tubes having diierent characteristics have likewise been omitted, since the use of such features under appropriate conditions will be appar-n ent to those skilled in the art. i

Moreover, while the illustratedA embodiment is especially adapted for use in automatic telephone systems, and in particular the relay system actuated by the anode current of the tube is of a type suitable for use in such systems, it will be apparent that oth'er types of controlled devices may be actuated by the anode current. likewise, different arrangements for selecting and applying the potentials to the two sides of the switching system may be employed, though the disclosed arrangement has particularv advantage when used with automatic telephone systems including a selector and register, or corresponding arrangements. I. What is claimed is: 1 1. An electrical control vsysteni comprising a vacuum tube having `a cathode, a control grid, a screen grid and an anode, meansfor Yvarying the potential of the control grid relative to' the cathodepotential, and control means connectedV to the screen grid and anode and operated by thev anode and screen grid currents only when the anode current is above apredetermined value and the screen grid current is below a predetermined value. l

2.Y A system as setforth in eiami 1 in which ated by screen grid current above a predetermined value.

3. A system as set forth in claim 1 in which the control means includes a relay connected to the anode and energized by anode current, and a cut-out relay connected to the screen grid and energized by screen grid current, an armature and back contact of the cut-out relay being located in the rst relay circuit, arranged so that the first relay will be energized only when the anode current is above a predetermined relay operating value and the screen grid current is below a predetermined relay operating value.

4. An electrical control system comprising a first source of potential, a second source of potential, means for varying one potential and means for arresting said variation when the potentials are matched, comprising a vacuum tube having a cathode, a control grid, a screen grid and an anode, means for applying potentials from said sources to the cathode and control grid respectively, and an arresting system connected to the screen grid and anode including means operated by the anode current only when the anode current ls above a predetermined value and the screen grid current is below a predetermined value- 5. An electrical control system comprising a rst source of potential, a'second source of potential, means for varying one potential and means for arresting said variation when the potentials are matched, comprising a vacuum tube having a cathode, a control grid, a screen grid and an anode, means for applying potentials from said sources to the cathode and control grid, an electrically operated arresting device, a control relay having an armature and associated back contact in circuit with the arresting device and a winding connected to the anode and energized by anode current above a predetermined value, and a cutout relay having an armature and associated back contact in circuit with the anode and control relay winding, and a Winding connected to the screen grid and energized by screen grid current above a predetermined value, arranged to deenergize the arresting device only when the anode current is above the former value and the screen grid current is below the latter value.

6. A system as set forth in claim 5 in which the means for varying one potential includes a series of contacts at different potentials, a brush and means for driving the brush into successive engagement with the contacts, and the arresting means comprises means for rendering the driving means ineffective.

HENRY F. HERBIG.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,903,837 Richardson Apr. 18, 1933 2,237,413 Clark Apr. 8, 1941 2,242,776 Clark May 20, 1941 2,380,950 Deakin Aug. 7, 1945 2,245,160 Schimpf June 10, 1941 

